Conventionally, a hot-pressing apparatus is widely known which causes upper and lower dies (a pair of dies) to press a workpiece, such as a steel plate, heated to above a temperature at which an austenite structure appears, and at the same time, to come in contact with the workpiece to quench the workpiece.
A technique on the hot-pressing apparatus is publicly known which enables the dies to suitably cool the workpiece during the quenching by providing water channels through which cooling water flows to the inside of the dies to cool the dies (for example, see Patent Literature 1).
However, gaps are formed, when the workpiece is quenched, between the workpiece and the dies by variation in the thickness of the workpiece caused by the press working, a precision error of the forming surface of the dies caused when the dies are manufactured, flexure of the dies during the press working, and the like. Consequently, contact areas between the surface of the workpiece and the forming surfaces of the dies decrease when the workpiece is quenched, which causes a problem that some parts in the workpiece are cooled at an insufficient cooling rate, and hardness of the workpiece is partly smaller than a predetermined value.